The invention relates to a circuit arrangement for the automatic adjustment of a two-wire full duplex data transmission system, in which a transmitter and a receiver in one station are connected via two lines to a further transmitter and a further receiver in another station, and wherein data flows in both directions between the two stations.
Known balancing resistors are formed from a plurality of parallel-connected time constant elements having adjustable capacitors and resistors. In the event of a change in the capacitance of the capacitors and a change in the resistances, not only the time constant of the relevant time constant element, but also the amplitude characteristics of the balancing resistor undergo a change. Due to the mutual influencing of the capacitors and resistors which must be adjusted, the desired compensation for these changes is time consuming and requires an iterative process of long duration. Thus, this process has the disadvantage that it can only be carried out by trained personnel. Further, the variable capacitances are generally constructed as fixed capacitors in combination with step switches, which requires a relatively large expense for construction.
A circuit arrangement is known for adjusting a two-wire full duplex data transmission system in which a plurality of parallel-connected series combinations are provided, and in which sub-currents flow from the transmitter to the receiver in the same station via the series combinations. These series combinations contain time stages and produce time signals which possess a determinate phase state to an edge of the data signal and determine the beginning and end of the sub-currents. Also the series combinations each contain an amplitude stage which emit amplitude signals whose amplitudes are adjustable. Although this known circuit arrangement very much simplifies the adjustment of the two-wire full duplex data transmission system, in many cases it can be advantageous to carry out the adjustment, not manually, but automatically.
An object of the invention is, therefore, to provide a circuit arrangement by means of which the adjustment of a two-wire full duplex data transmission system can be carried out automatically.